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Guest post – John Church: What we think we know, and what it might mean for predictions and possible mitigation strategies

This is a guest post by John Church. John is an oil and gas professional and has spent some 30 years working for one of the biggest oil companies in the world.

The key uncertainties in this epidemic are how far and fast the infection has spread, and what the mortality is. There are lots of other variables and uncertainties about who gets affected (sex, ethnicity, BMI, BCG or not, whether being infected grants immunity thereafter, etc.). But let’s just use the information we have to try and work out approximate averages for infection spread and mortality (age dependent).

Based on the Diamond Princess cruise ship (DP) and early Italian hospital info we can deduce a few things:

1) No one under 40 seems to get seriously ill, if any symptoms at all. Yes, there have been a few highlighted cases in the media, but the numbers are very, very small.

2) We know from the DP data that there were 711 confirmed infections and ~20% required hospital. We know that this resulted in 12 or 13 deaths.

3) We know that mainly its people in their 60s and 70s that go on cruises. The age distribution on the DP infections is below.

4) We know that chance of hospitalisation and also mortality steadily increases with age.

5) We know from hospitalisations in Italy that ~14% of people above 80, and ~ 7% of people in their 70’s were dying. Probably higher than it might have been if they hadn’t run out of critical capacity, but let’s stick with these numbers.

6) About 7% of hospitalised patient deaths in the UK are under 60.

7) We know the population distribution in the UK:

>80                    3.3mln                    ~5%
70-80                 5.5mln                    ~8%
60-70                 7.0mln                    ~11%
50-60                 9.0mln                    ~13%
40-50                 9.1mln                    ~14%
<40                    32.8mln                  ~49%
Total                 66.7mln                  100%

The Diamond Princess (DP)

Using the age distribution of the passengers and looking at the observations (hospitalisations and fatalities), it is possible to create an age dependent infection model. On the Diamond Princess there were 711 cases and 12 deaths. Approximately 20% of cases required hospitalisation. The approx. age distribution of cases was >80 = 9%, 70-80 = 38%, 60-70 = 29%, 50-60 = 9%, 40-50 = 4% and <40 = 11%. A model which gives a good match to this data, fits the Italian hospital mortality data and honours the basic observations is below :

Age        % hospitalised      Hospital death rate    Mortality (all infections)
>80        ~ 40%                      ~14 %                            5.6%
70-80     ~ 30%                      ~ 7 %                             2.1%
60-70     ~ 20%                      ~ 4 %                             0.8%
50-60     ~ 10%                      ~ 2 %                             0.2%
40-50     ~ 1%                        ~1 %                              0%

This needs to be seen as a working model, but based on some solid observations. It can be adapted as more information come in.

So if this scenario was correct, what would it mean in the UK if everybody caught the disease? Or if we limit the spread until 60% herd immunity ?

Age         Calculation      Deaths       %             Deaths (if assume 60% herd)
>80          3.3 x 5.6%        185k          49%         111K
70-80       5.5 x 2.1%        116k          31%         69k
60-70       7.0 x 0.8%        56k            15%         34k
50-60       9.0 x 0.2%        18k            5%            11k
40-50       9.1 x 0.01%      1k              0%            <1k
Total                                  375k                           225k

So this would mean over several waves of infection, without vaccine and under current treatments we could have ~375k deaths if everyone caught it, but might expect to have a maximum of ~225k deaths assuming up to 60% of the population gets infected.

So what does this mean for average mortality and infection spread in the UK?

Well, if everyone caught it and we had 375k deaths, that means an average mortality of ~0.5%. About 5x that of common flu. Does that seem reasonable ? I see this as a bit of a worst case as it’s based primarily on the Italian data which may have had higher mortality due to the fact they exceeded their critical care capacity, and it also assumes we don’t learn which treatments are most effective as we progress.

What about spread of infection in the UK?

It looks as though this current wave of deaths will be ~ 35k, if we assume we have just passed the peak and we assume approximately one-third deaths before the peak and two-thirds after (as per Italy and Spain apparent distributions). In that case we would have already infected 35000/0.5% = about 7 million people (approximately 10% of population). But we also need to factor in that there are lots of deaths happening outside hospital (beyond the 35k). Analysing Holland vs Belgium (where they count all deaths, not just hospitals), it appears as though there are approximately double the number of deaths in Belgium (current rates are 202 deaths/million in Holland and 445 deaths/million in Belgium, according to the Times 18/4/20). And recent reports suggest 7500 care-home deaths, which would result in a 50% increase compared to hospitalised numbers. If we assume an additional 50%, this would result in approximately 50 000 deaths in the UK as part of this first wave, and that means 50000/0.5% = 10 million infected already (~15% of population).

So how about the geographic distribution?

We should assume a concentration in urban areas. I read somewhere today that a third of all UK deaths come from London. If that is the case then we have >12 000 deaths (1/3 of 35,000) in London hospitals in this wave, with maybe 18 000 total if we assume care home deaths result in a 50% increase to get the real number. With a mortality of 0.5%, this would mean some 3.5 million people in London have been infected, approx. 40% of the population of 9 million. So more infections in big urban areas but offset by lower rates elsewhere. As might be expected. It would also explain why so many famous people who live and work in London have been infected. Clearly there has been very widespread infection in the city.

What about spreadrate?

The DP timeline showed a two-week period between when a Covid-positive passenger embarked the liner in Yokohama on Jan 20th and Feb 4th when the ship was placed in quarantine. How often do we need to double the cases to get from 1 to 711 ? Well, it turn out that this needs a doubling rate every 1.5 days. Or the same passenger managed to infect 700 other people. Or a combination of superspreading in a confined environment and also a rapid spread rate. Either way, in a confined environment the spreadrate was very fast and efficient. Regarding the UK situation, given that the first cases came into the UK in early/mid January from China (returning students) and also from European ski resorts, and we didn’t enter lockdown until March 23rd, there is more than enough time for a very large number of people to get infected. There are 10 weeks between mid -January and March 23rd (lockdown day). If we assume infections double every 3 days, that’s 23 ‘doublings’ and results in over 8 million cases. This is in line with the DP and Italian data which predicts between 7 and 10 million cases as above. A study done by Oxford University stated a high case scenario of 50% infections (> 33 million people), but this is probably unlikely as this would lead to much lower mortality than shown by the DP and Italian data.

So what does this mean for the future?

Once the current (first) wave has diminished, and restrictions are eased, there will be a continuation of infections. However, if we already have 10-15% infection rates (with up to 40% in urban areas) the second wave will be slower and lower. In urban areas the higher previous infections will mean it spreads slowly, and in less populated areas the lower population density will mean slower spread. So we will see nothing like the firestorm we have seen in the first wave. If we look at the 10-week timing from arrival in UK (mid-January) to lockdown for the first wave, we could predict another (second) wave in about 2-3 months from the ending of restrictions. So assuming we relax restrictions in early May, then we could predict a second wave during August and September or sometime beyond. Based on 50 000 deaths due to the first wave (hospital and non-hospital), by the end of the year we might expect an additional 25 000 to 50 000 deaths. But from a purely forensic point of view, this will increasingly manageable as each wave will be less of a problem than the previous.

What should we be doing?

I’m not an epidemiologist, but it would seem to me, based on the calculations above, that this is very infectious and spreads very fast (7-10 million cases in the UK already), has an average mortality of ~ 0.5%, doesn’t damage younger people at all, is relatively low risk for anyone less than 60, and the NHS has been shown to cope with the first and largest wave, so we should protect older at-risk people through isolation as best we can and let this thing run its course as fast as possible. Once 60% have had it, the risk diminishes for everyone. There is no point applying a containment strategy, as you suffer the economic consequences but gain none of the benefits of increased population immunity, because everyone will get infected anyway. This can be seen from the Singapore data right now. Australia and NZ will be test cases when they re-open their economies. They have not even had a ‘first wave’, so will there be a surge of cases 2-3 months after they ease restrictions? And we should continue to monitor Sweden who have not put in place stringent isolation for the majority of their population: if there is no escalation to an out-of-control situation, it tells you we should just look after older people but let it rip through everyone else. ASAP.

So, there are 3 key reasons to get this through the population as soon as possible,

1) Economic: the faster this is over the less the economic downturn. We should have all younger people working now, but getting the full workforce back as soon as is practical.

2) Societal: minimise the time older generations and those ‘at risk’ must remain in isolation. It is not healthy, physically, mentally and from a societal perspective, to have this in place and the negative impacts are not fully known.

3) Medical: being exposed to this virus sooner means that everyone is younger when it happens. Given that this is a virus which gets worse with age, it makes sense to be exposed to it as early as possible.

What if it turns out there is no immunity and people can get re-infected?

Well, we are just going to have to live with it until a vaccine is found. Mortality will decline even in older people as we understand better how to treat people. The problem will just fade away and become part of life and death.

How does all this compare to ‘business as usual’?

An expected death toll of 225k overall (50k in this first wave) sounds like a lot of people, but we must remember that this is only 5 months of normal deaths in the UK which occur at around 50k per month. According to hospital reports, 90% of those dying have serious co-morbidities, particularly cardio-vascular disease and high blood pressure, and many would have died shortly anyway.

According to Professor Johan Giesecke (pers. comm.), who is a Swedish epidemiologist advising the Swedish government and also the WHO, in order to ascertain the ‘lethality’ of the epidemic we need to remove these cases. Doing so (removing 90% of the cases) would reduce the 0.5% mortality figure to a ‘lethality’ of around 0.1%, which is what a normal healthy population should consider. This is approximately the same as a bad flu epidemic. We will only know this when we review the whole of 2020 and see how the total UK deaths compare (month by month) to long term averages. It is these excess deaths which ultimately determine the true nature of the epidemic.

Whatever else we do, we should continue to look at the Swedish situation. If they have managed their pandemic successfully without population-wide enforced isolations we should definitely not put all our healthy young people into lockdown again.

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43 thoughts on “Guest post – John Church: What we think we know, and what it might mean for predictions and possible mitigation strategies

  1. We have some very good reality checks for the Diamond Princes, Theodore Roosevelt & Charles de Gaulle.

    Similar situations, but with a different age cohort. One death out of something like 2000 recorded infections.

    From what I can see, there is no reason anyone under 60 can’t be out and about living a normal life. People above 60 should be able to do their own risk assessment.

    Rest homes etc should have strict controls, which are going to be far more effective and successful if everyone that support these operations were free to act, rather than cowering in a hole.

  2. “we should protect older at-risk people through isolation as best we can and let this thing run its course as fast as possible.”

    Well stated! That has been the obvious course of action since the data from the Diamond Princess case became known.

    It is a little unclear how you reconcile the 375k forecasted deaths to the predicted 35k current wave. Since it is becoming increasingly clear that only those with already compromised health are at any significant risk from C-19 — and since each person can die only once — it is a safe bet that the total All Causes deaths for 2020 will not be 50% higher than the usual 550k. Indeed, the total is unlikely to be 5% higher — although some deaths will be accelerated by a few months and many deaths may be listed as C-19 instead of flu, heart disease, cancer.

    However, if the economic devastation from the unnecessary lock downs results in major civil disturbances or disruptions of essential supply chains (power, water, food), all bets are off.

  3. I do worry we are forced to add the “nice phrase” and the “nice sentiment” of “protecting the elderly”: as though they were a particularly delicate dahlia bulb; that needed to be kept in the sunnier side of the greenhouse all winter; if we all think of our lives like that, well fine.

    At times I feel it is like “the bomber will always get through:” we can all feel like chanting spells; scratching our left nostril 3 times; hopping twice every ten yards; to try and ward off malevolence, but ultimately viruses seem to suit themselves; and maybe everyone is wasting their time with these lofty and highly admirable and totally praiseworthy and completely well-intentioned sentiments; and who asks “the old folks” what they think and want anyway: do we not patronise them by making arbitrary rules: over-70 can’t do this; 3 months ago this would have been “ageist” and fiercely condemned on social media.

  4. What was the proportion infected if the total in the cruise ship? 700 out of 3700. Doesn’t that imply a huge number are either naturally immune or exhibit no symptoms at all. Infection rates in entire nations will never be as high as on a cramped cruise ship. The assumptions that such a large proportion of could catch it therefore seem conservative to me. It also implies that after this initial wave there may already be some herd immunity if half are immune and 10% had it already. I’m also not convinced that all 12 could be attributed to covid, how many if the 12 would be dead anyway? Remember cruise ships contain the newly wed and newly dead.

  5. ” Doesn’t that imply a huge number are either naturally immune or exhibit no symptoms at all”

    Hard to say, but there is an indication that even in close quarters most people either don’t get it or don’t have any symptoms.

    There at least three populations that show this.

  6. Whether or not everyone becomes immune after catching the disease it is plain that most people do, else there would be nothing to reduce the spread of the disease.

  7. Good piece.

    Also, many of the weaker and at risk stock (sounds like an awful term in this context) will be taken in the first wave. Therefore, could we expect less people to die as we go forward?

  8. Excellent thought through analysis based on best data available. My own analysis of England and Wales death rates from all causes would suggest, as mentioned, that ‘younger’ people are not at significant additional risk from Covid-19. So at least those under 50 should be free to go about their lives, with all others isolating for 3/4 weeks to see what the effect is. I am sure I will be wrong – but by what degree?

  9. If we look at the 10-week timing from arrival in UK (mid-January) to lockdown for the first wave, we could predict another (second) wave in about 2-3 months from the ending of restrictions.

    This seems unlikely. The first wave started out from a handful of cases. There must be at least tens of thousands of actively infectious people now. Even allowing for a slower spread rate I think the second wave will be noticeable quite quickly.

  10. “What if it turns out there is no immunity and people can get re-infected?

    Well, we are just going to have to live with it until a vaccine is found.”

    Surely, if people do not acquire immunity, the same (lack of a) mechanism would render a vaccine ineffective?

  11. This is indeed a worry for a vaccine. It is likely that even if a vaccine is developed, it would be like the flu vaccine, and have to be changed every year (and probably be ineffective half the time).

  12. How many diseases are there actually where there is no immunity? Have we seen loads of reinfections? We should surely have seen some by now in the UK, as we’ve been locked down for over one reinfection cycle. So there must be some sort of immunity. If it’s short then this lock down could be disastrous, as it’d spread the disease out over longer than the immunity lasts thus ensuring that people get it more than once!

  13. I think the 711 confirmed cases are confirmed because they were all tested. So it includes asymptomatic cases. My feeling is that the reason there were only 711 out of 3700 is just a function of the spreading mechanism and the time. It only had 2 weeks and that was the result. Had there been another 2 weeks I suspect almost everyone would have been confirmed positive in that kind of environment.

    As an aside, if you wanted to conduct an experiment on the infectivity etc of this, you could not have designed it much better than what happened on the DP. It’s an almost perfect dataset.

  14. Many of the feeblest old things in care homes are not fit to make decisions for themselves. So too, I imagine, people in mental hospitals.

    So those are the dependent populations that need conscious protection from and by the rest of us. Chipper 70-year olds living competently in their own houses need not be treated in the same way.

  15. Well said Terry. Well I am 75 in a few weeks. It is an awful thought, because on my birthday I become nearer 80 than 70!! I am pretty healthy for my age

    I said right from the start that C-19 would prove to be little worse than a bad flu, and despite lots of hype since, I see nothing to change that view. Like all Influenza Like Illnesses (ILI) it takes the old and infirm, and unlike a number of bad flu viruses it thankfully spares the children in the main.

    When 28,000 died of Flu in 2014/15 the government never even noticed – did anyone? What happens when we get a winter like that one again (it is 17,000 average per season) – more lockdown, more economic ruin?

    I would take my chances out in the community, taking sensible precautions to avoid congested areas and obvious risky behaviours. They are now ruining what I have planned for what is left of my life, and they are saddling my children and grandchildren with even more debt. Baby boomers (I’m a bit old) have often been categorised by youngsters as selfish folk who have pinched all their money – now we need to ruin the country to keep us all alive!!!! Most of us don’t want that, not at the expense of the younger generation.

    As Prof.Sullivan says in a Telegraph article form a few days ago – “I think the fear out there is extraordinary. Now, it’s our view that the fear is out of all proportion to the threat and the risk. There’s been a real perspective loss here.

    “I keep saying to people we have as many if not more people dying of pneumonia and loads of other conditions. I think life has to start renormalizing again with sufficient care and attention to the vulnerable.”

    Well said Sir.

  16. Hector – You spotted the plan. It is going to be like Office 365 – a monthly payment and who will be supplying the vaccines??? Bill Gates who funds Imperial College.

    Once you are on the plan, you will be on the end of a needle for life, and the idea is that if you say “no” you won’t be allow to travel or go out at all – all checked by your mobile phone.

    Welcome to The Brave New World??

  17. I agree this is good analysis, with one exception, a rather important one. The DP had a limited population, we have no idea that if was double or treble the size that the deaths would not have been the same. So the 0.5% might be out by a factor of 2, 5 or anything for that matter, ie it might be a lot less.
    I agree that lockdown should be removed asap, and that over 70s should be given the choice to determine their own futures. We should not be tempted to use ‘soft’ coercion to lock them up semi-permanantly.
    The age profile of deaths recorded ‘with’ cv-19 is identical to all deaths. This begs the question, has anybody actually died ‘of’ cv-19 or rather all just ‘with’ cv-19?

  18. I had to have my smallpox vaccination and several other jabs that were certified, depending on destination, in order to be able to travel in the 1960s and 1970s. I recall that health control preceded immigration: if you didn’t pass that, you were on your way out again with no questions and no right to even phone the consul. So airlines checked at check-in, and ships prior to boarding.

  19. New study in New York sampling 3,000 haven’t seen details but reports 14% infection rate which would give a mortality rate of 0.5 as suggested above.
    Though as New York is an example of a bad hotspot scenario that would suggest that actual rate is lower when spread across an entire country.
    New York did have a TB epidemic a few years ago so still interested in how that factors in to mortality and hotspots.

  20. You could avoid the awful term by simply omitting it: “many of the weaker and at risk…”

    With my editor’s hat (or green eyeshade) on…

  21. Your reasoning assumes that the test is reliable and accurate. The accounts of it that I have seen suggest that it is neither. People who “test positive” might have some other coronavirus (such as a common cold). Or, in the view of the rate of false positives (up to 80%) nothing at all.

  22. As a hospital doctor this theory being propagated that this is just like influenza or that people are dying “with” Covid19 but of natural causes or comorbidities is nonsense. Evidence: 1000s of critically ill people in their 50s 60s 70s that do not respond in that way to influenza. Plus 2 weeks of massive up tick in deaths from ONS mainly (in my opinion almost all) associated with Covid19. I agree with a lot in the article, but I would take issue with 90% deaths being inevitable or within the last months of life. The great majority of persons with comorbidities have long useful lives in front of them.

  23. Good data … thanks for sharing. The model I built is focused on predicting fatalities, and has the broad assumption that there is no need to worry about people under age 40. A warship will have a very low average age. So having zero or maybe 1 fatality might seem about right (out of 840 cases).

  24. Well that’s very strange, it doesn’t really fit with 50% of deaths being in care homes. The average length of time spent in a care home is a lot less than that: https://www.researchgate.net/publication/51014346_Length_of_Stay_in_Care_Homes

    Quickly looking up https://www.ssa.gov/oact/STATS/table4c6.html

    Average male from 78 – 9 years, average Female from 81 – 9 years. But people with Comorbidities are going to be lower than that. I can’t see how you could get to greater than 10.

    That suggests that if 50% of deaths are loosing on average 1.2 years of life, the other 50% must (reasonably) be losing about 18 years of life. Given that average age of death is around 78 I suggest that the Glasgow study is nonsense.

  25. …according to reputable research years of life lost as a result of dying of Covid19 is greater than 10 on average.

    OK, let’s factor that in and follow it through.

    Most of the rest of health care is currently closed. Tens of thousands of people with life threatening diseases (which, if treated, can be ameliorated) are no longer being checked and treated. How many years of lost life are we looking at?

    If we continue the lockdown the economy will be trashed. This means (apart from all the other catastrophes) a lot less wealth available to redistribute to health care. Along with everyone else, the NHS will be impoverished. How many years of lost life are we looking at then?

    It’s pick your poison. Poison-free is not available.

  26. It is true that neither (nor anybody else) can exactly know how long someone who died having contracted Covid19 might otherwise have lived for. But there are some things we do know.
    1) The average age of Covid deaths in the UK (from data week ending April 10)is ~ 78
    2) Male life expectancy in the UK is ~79.

    From this we can deduce that the assertion that the average years lost due Covid is more than 10 is false, especially given that 91% of the deaths occur in people who have serious underlying health issues.

  27. “2) Male life expectancy in the UK is ~79.” No, male life expectancy at birth is 79. Male life expectancy at 78 is probably a good few years. By all means look it up and warn me if I’m wrong.

    My own guess is that the analysis from Glasgow involves hospital deaths, including the non-old. By contrast the slaughter in the care homes is probably bumping off ancients, and particularly the ill, who can expect only a few more weeks or months of life.

  28. You guys are clearly not actuaries, nor understand how life expectancy works (except dearieme). If you are male and reach the age 77 years you can expect on average to have another 10 years of life. This will vary up or down depending on comorbidites. If you are a 77 year old male and you die of respiratory failure caused by Covid19 you will on average have been deprived of 10 years of life. That’s how it works.

  29. P.s. I agree that there is an additional and less well quantified loss of life in care homes and years of life lost in that group will be less, even before talking about quality of life.
    PPS I also agree that the other side of the equation I.e., loss of life as a side effect of lock down needs to be examined. My beef is with the group that either say it’s just flu or its a bit worse than flu but not shortening useful life. Neither are true.

  30. This issue has been discussed previously on here (or perhaps it was just on my Twitter) in relation to Toby Young’s Critic article and response. As Young says:

    “Bowman’s article says I underestimated the life expectancy of those at risk when I pointed out that the average age of Covid-19 fatalities is 79.5 and life expectancy in the UK is 81. He points out, correctly, that people who live until 80 have an average life expectancy of nine years. However, according to data from Wuhan, 67 per cent of Covid-19 fatalities have significant comorbidities and therefore have a shorter life expectancy than nine years. As a rule, elderly persons with comorbidities should have their life expectancy adjusted downwards by three years, giving an average life expectancy of those at risk of six years.”

    I suspect we’re really talking less than six years. Bear in mind that we’re being told that care home Covid deaths are significantly under-reported, and that changes things greatly, because half of those in care homes die within a year (can’t remember the exact figure, but something like that).

    I would also be careful of applying that Glasgow work too directly to the UK, as they’re getting their data from Italy, which is a significant outlier.

  31. My beef is with the group that either say it’s just flu or its a bit worse than flu but not shortening useful life.

    I don’t think there are too many of those here. Most of the discussion relates to the justifications for the lockdown. People make overall outcome comparisons with flu but that’s fair and it’s not saying they are the same (the U of Glasgow piece compares COVID-19 outcomes with coronary heart disease and pneumonia).

  32. Afterthought. Of the non-old who are dying, how many consist of staff from hospitals, care homes, and so forth? A non-negligible proportion?

  33. Beginning to think the the millennials just want a crisis of their own so that they can say, but we lived through…..

    They are least at risk, but seem the most panicked, I’ve experienced and heard of so many stories of 20 yr olds lecturing their parents its silly.

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